Chronic liver disease is marked by the gradual destruction of liver tissue over time. Several liver diseases fall under this category, including cirrhosis and fibrosis, the latter of which is often the precursor to cirrhosis. Cirrhosis is the result of acute and chronic liver disease and is characterized by the replacement of liver tissue by fibrotic scar tissue and regenerative nodules leading to a progressive loss of liver function. Fibrosis and nodular regeneration results in the loss of the normal microscopic lobular architecture of the liver. Fibrosis represents the growth of scar tissue resulting from, for example, infection, inflammation, injury, and even healing. Over time, the fibrotic scar tissue slowly replaces the normal functioning liver tissue resulting in a decreasing amount of blood flow to the liver leaving the liver incapable of fully processing nutrients, hormones, drugs, and poisons that are found in the bloodstream. More common causes of cirrhosis include alcoholism, hepatitis C viral infections, ingestion of toxins, and fatty liver, but many other possible causes also exist.
Once any cirrhosis or fibrosis has occurred in the liver, it is generally considered irreversible. Rather, conventional treatment focuses on preventing any further progression of cirrhosis in the liver and mitigating the complications that can arise from cirrhosis. In more advanced stages of cirrhosis, the only conventionally known treatment is a liver transplant. The American Liver Foundation estimates that over 300,000 people in the United States are hospitalized each year as a result of cirrhosis of the liver. It is also estimated that 18,000 people are in need of liver transplants.
Chronic liver disease can also lead to hepatocellular carcinoma (HCC). HCC is the fifth most common cancer worldwide and has the fourth highest mortality rate. Unlike patients with other cancers, such as lung cancer and breast cancers, more than 95% of HCC patients die within five years of being diagnosed with HCC. Although HCC is the subject of continuing investigation and its symptoms are well known, early-stage diagnosis of this disease remains difficult and the survival rate after diagnosis is very low (3%-5%).
Thus, there remains a great need for early diagnosis and treatment of these liver diseases.